Urban Jungle: Jakarta’s Green Wall

This is the third post in Human Nature’s “Urban Jungle” series, which explores the inextricable connections between intact ecosystems and thriving cities.

Jakarta, Indonesia

Panoramic view of Jakarta, Indonesia’s capital city. Jakarta’s more than 12 million residents depend on fresh water that flows from nearby forests. (© Warren Goldswain)

These days, Jakarta is defined by polluted waterways, smoky air and traffic congestion. Over the past few decades, the environment surrounding Southeast Asia’s largest city has been quickly deteriorating due to rapid population growth and the lack of proper urban planning.

After spending a few years as one of Jakarta’s more than 12 million residents, I moved to Bogor, a smaller city near the forested Gedepahala region. In fact, many city dwellers often spend weekends and holidays in Gedepahala, as it’s the closest area we can visit to get fresh air, enjoy the rivers’ cold, clean water and see wildlife.

But forests do much more than provide a weekend refuge for urbanites. They also store fresh water cities depend on — and keep it from descending on those cities all at once.

Growing up in rural Bali, my family was among the local farmers practicing subak, a traditional water irrigation system used to grow rice. During this time, I observed that our rivers and water irrigation systems would only be filled if the forest upstream was left intact.

Clean water from Gunung National Park flows down to the nearby village of Bodogol. Local people use this water for their crops, collecting food, and bathing. (© Jessica Scranton)

Clean water from Gunung Gede Pangrango National Park flows down to the nearby village of Bodogol. Local people use this water for their crops, collecting food, and bathing. (© Jessica Scranton)

More recently, as a professional diver and marine scientist, I have learned that even coral reefs rely on a healthy forested landscape onshore. This reduces sedimentation in the ocean and allows coral reefs to flourish.

When I first moved to Jakarta, I became curious about the city’s challenges with annual flooding. Most Jakarta residents claim that the flooding is caused by excess water flowing from Bogor, which is upstream from Jakarta. I think this perception is probably true to a degree, combined with the fact that growth of paved areas in Jakarta limits the water’s ability to sink into the soil.

In the 1980s, whenever there were big rains in the Bogor area, flooding was not a major issue in Jakarta. In the last 10 years, however, even three days of heavy rain in Bogor have been enough to create massive flooding in Jakarta, killing dozens of people. Twenty years ago, the coral reefs in the Kepulauan Seribu Marine National Park in Jakarta Bay were thriving; today, they have mostly disappeared due to sedimentation from upstream.

In fact, flooding has gotten so bad that the city is considering building major infrastructure, such as dikes or dams, to control it. However, there may be a cheaper, easier solution at hand: reforesting the land upstream.

reforestation project, Gunung Gede Pangrango National Park, Indonesia

A community member walks through CI’s reforestation project in Gunung Gede Pangrango National Park. (© Jessica Scranton)

Through CI-Indonesia’s work in Jakarta’s watershed, we have learned that two national parks within the Bogor area — Gunung Gede Pangrango and Halimun Salak — are part of a crucial landscape that regulates the flow of water to Jakarta.

This 135,000-hectare (almost 334,000-acre) landscape, collectively known as the Gedepahala, is one of the largest remaining contiguous forest areas in Java.

It produces about 231 billion liters of water per year which benefit around 30 million people, including residents of major cities such as Jakarta, Bogor, Tangerang and Bekasi.

The landscape also harbors significant biodiversity, including several endangered species found nowhere else, such as the Javan gibbon, Javan langur, Javan hawk eagle and Javan leopard.

However, deforestation and land-use conversion from forest to agriculture plots and settlements pose a serious threat to the viability of this critical watershed. As I’ve driven around the outskirts of the city, I’ve witnessed that most of the steep-sloped land has been converted into cropland.

Javan gibbon, Indonesia

Javan gibbon, one of the threatened species that is native to Indonesia’s Gedepahala region. (© Conservation International/photo by Sunarto)

All in all, about 15,000 hectares (more than 37,000 acres) in the watershed are no longer forested. Without vegetation to hold the water in place, increased water runoff leads to flooding downstream.

Over the last five years, CI has been working with many partners, including local businesses and communities, to pursue a number of initiatives, including:

  • Reforesting the watershed by planting around 1.2 million native trees on the edge of Gunung Gede Pangrango National Park. These trees act as a “green wall” that separates natural and degraded areas and helps buffer the park from the impacts of development.
  • Establishing a Javan gibbon center, a rehabilitation and education facility that raises awareness about the value of wildlife conservation within the general public.
  • Creating a small-scale hydropower facility that irrigates nearby croplands while also providing clean electricity that powers local homes.

Collectively known as the Green Wall project, these activities are done together with the local communities who live near the national parks, as well as the park rangers and business communities.

I have been delighted to witness how happy the farmers become when they realize the huge role of the forest in maintaining the waters, and that they can use technology to get even more use out of the water flowing from the forest.

hydropower project, Gunung Gede Pangrango National Park, Indonesia

A small-scale hydropower project has brought electricity to families near Gunung Gede Pangrango National Park who had been living off the grid for years. (© Jessica Scranton)

And here’s an interesting twist: this whole project may not have been possible without the help of a company based thousands of miles away. Daikin Industries, a Japanese company that manufactures air conditioners, has been supporting this project since 2008.

Today, the company announced that it will invest US$ 4.5 million over 10 years to support critical forests in Indonesia and five other globally important forests where CI works in Brazil, Cambodia, China, India and Liberia  — a true testament to the success of our work  with this single project in Indonesia. This endeavor will focus on forest conservation, agriculture and other environmental education activities on a global scale, aimed at reducing CO2 emissions and safeguarding some of Earth’s most critical forests for human well-being.

As we continue to reforest Jakarta’s watershed, I expect that eventually the flooding in the city will lessen. And since climate change is predicted to increase the frequency of extreme weather events like floods, conducting projects like these will become even more critical to protect our cities across the globe. I hope more companies will follow in Daikin’s footsteps.

Ketut Putra is the vice president of CI-Indonesia. Read other blogs in our “Urban Jungle” series.


  1. V. Ralph Clark says

    Fantastic!! The most practical & cheapest solution to urban problems is usually to restore ecosystem functioning so that it serves its original purposes. Selling that to engineers is the tricky side of it…

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